Pollinators and Predators in Hawai`i – Field Report

Rescuing Species and Interactions in the Extinction Capital of the United States

by Dr. Clare Aslan

It’s probably not your typical view of Hawai`i: we’re standing at 6000 ft in elevation, on a windswept flow of broken and jumbled lava near the saddle between the great shield volcanoes, Mauna Kea and Mauna Loa. A large herd of wild goats browses the tufted grass dotting the pu`u, or cinder cone, to our east. In front of us is a fenced tract of mixed a`a and pahoehoe, occupied by a mingled array of native shrubs and a few solitary trees. The matrix among the shrubs is heavily invaded by waist-high fountain grass (Pennisetum setaceum). We climb the fence, which keeps the tract free of invasive sheep and goats and pigs, and begin to push forward through the grass and brush. There is no path. The jumble of rocks can be treacherous, especially where we can’t see our feet because the grass is so thick. We stumble and scramble across the landscape. Orienting, however, is easy: Mauna Loa’s gentle bulk is in constant view to the south, Mauna Kea’s cindercones rise to the north, and the hazy blue of the sea can be seen to the east and west. The day is so clear, in fact, that we can see Maui’s Haleakala, hovering like a cloud beyond 26 miles of ocean to the northwest.

Aslan study site with Mauna Loa

Study site with Mauna Loa in the background. Photo cred: Clare Aslan

After a 40-minute slog, a few bruises, and some fresh gashes in our boots (which never last long in this landscape), we make it to our first point: a randomly-selected GPS location in a little dell. Close by is a spindly Solanum incompletum bush—noticeable by the flash of bright flagging warning researchers to keep their distance. This is one of only a few dozen S. incompletum individuals remaining on the island. In spite of the remarkable orange thorns growing on the surface of its leaves, S. incompletum is no match for the invasive browsers and has come close to slipping into extinction.

We flag the point and set about placing our ant bait jars: small, uncapped vials holding a delectable mixture of corn syrup, tuna, and peanut butter. We deposit five bait jars in a loose ring around our GPS points and head off to the next random point. We’ll be back in a couple of hours to check the baits, working in a circuit through as many points as we can get to today.

Bidens menziesii with volcano Hualalai in the background. Photo cred: Clare Aslan

Bidens menziesii with volcano Hualalai in the background. Photo cred: Clare Aslan

These questions strike at the heart of a new research challenge for me: how do local-scale processes such as pollination influence huge, landscape-scale factors such as diversity? Biological invasion, climate change, and habitat fragmentation are landscape-scale issues, while species interactions such as pollination occur at the local, individual organism scale. Scaling up from immediate interspecific interactions such as disruption or restoration of pollination to large, landscape-scale diversity, community patterns, and adaptive pathways is currently both experimentally and mathematically daunting.

In Hawai`i, our research on pollination restoration via predator eradication may generate usable management techniques that could enable the conservation of desperately-endangered plants in these remnant protected sites. At the same time, we hope to find clues to cross-scale conservation planning in other systems. In the meantime, we will fend off mice and rats and yellowjackets and ants in bubble-like safe zones, high on the slopes of the largest and most isolated volcanoes on the planet, hoping for mini pollinator population booms.

Entomologist Will Haines checking an ant bait

Entomologist Will Haines checking an ant bait

These questions strike at the heart of a new research challenge for me: how do local-scale processes such as pollination influence huge, landscape-scale factors such as diversity? Biological invasion, climate change, and habitat fragmentation are landscape-scale issues, while species interactions such as pollination occur at the local, individual organism scale. Scaling up from immediate interspecific interactions such as disruption or restoration of pollination to large, landscape-scale diversity, community patterns, and adaptive pathways is currently both experimentally and mathematically daunting.

In Hawai`i, our research on pollination restoration via predator eradication may generate usable management techniques that could enable the conservation of desperately-endangered plants in these remnant protected sites. At the same time, we hope to find clues to cross-scale conservation planning in other systems. In the meantime, we will fend off mice and rats and yellowjackets and ants in bubble-like safe zones, high on the slopes of the largest and most isolated volcanoes on the planet, hoping for mini pollinator population booms.

Research team

Research team, photo cred: Christina Liang

3 thoughts on “Pollinators and Predators in Hawai`i – Field Report

  1. Hi Colm: Thanks for your interest! We don’t know that ants are pollinators in this system, although there is a lot of “accidental” pollination that occurs in any plant-pollinator interaction…that is, an ant just crawling on flowers in search of food could inadvertently transfer some pollen on her body or legs. In this system, the main concern is that ants are predatory and ground-nesting, and that the pollinators in many cases are also ground-nesting. The ants will therefore prey on the larvae of the pollinators, reducing the number of pollinators in the area. There are no native ants in Hawaii, so this kind of an impact is something the pollinators are unprepared to deal with. For that reason, we plan to exclude ants from our pollinator refuges, to see if pollinator populations and activity are higher when there are no ants in the immediate vicinity.

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